Very confused?

I’m new to this but I decided to come on here and see if I could get any answers to what’s going on. So whenever my gf decides to finger me, 9x out of 10 I start to bleed. I don’t know what the problem is because I’m not in pain after it happens just confused on why I’m bleeding. Sometimes it’s a lot of blood and it kinda scares us. So we’ve stopped doing things till we can figure things out. Any of you ladies have the same problem or any suggestions of what’s going on?